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Flashcards in Cataracts Deck (23)
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1
Q

What are cataracts?

A

Vision-impairing disease characterised by gradual, progressive loss of transparency of the lens
It is one of the leading causes of visual morbidity and blindness worldwide

2
Q

What are posterior subscapular cataracts?

A

lie in front of the posterior capsule
manifest as vacuolated or plaque- like appearance
they are associated with steroid use and DM
patients have particular trouble with bright sunlight/oncoming headlight
reading vision is affected more than distance vision

3
Q

What are cortical cataracts?

A

Opacities which start as clefts and vacuoles on the cortex between lens fibres
subsequent opacification leads to radial spoke like opacities
They are closely related to environmental stresses
E.g UV exposure, diabetes and drug ingestion

4
Q

What are nuclear cataracts?

A

Nuclear sclerosis characterised by a yellowish hue and in later stages a brownish discolouration
Have a correlation with smoking, with calcitonin and milk intake

5
Q

What can age related cataracts be exacerbated by?

A
Allergy
Hyper/hypotension
Mental retardation
UV light
Infrared radiation
Diabetes
6
Q

What are congenital cataracts?

A

Detected at birth
Jevenile cataracts develop in first 12 years of life
1/3 are inherited
Can be total or partial:
Partial:
Polar- anterior or posterior
Zonular- lamella, stellate sutural or nuclear

7
Q

What are traumatic cataracts?

A

Iris is torn away from its normal insertion causing shrinking and damage
needs to be sutured and allowed to repair before reconstruction occurs
Blunt- rosette-shape appearance or are of the PSC variety
Penetrating- whole lens can become cataract if large, or leave an opacity that is localised to site

8
Q

How can cataracts be divided by their maturity ?

A

Immature
Mature- cortex completely opaque
Hyper-mature- small and wrinkled lens material due to leaking out of material

9
Q

What are the clinical features of cataracts?

A

Decreased visual acuity: gradual progressive deterioration and disturbance in vision (PSC can result in reduction in near acuity more than distance vision. Nuclear sclerotic cataracts have decreased distance acuity and good near vision)
Glare- decrease in contrast sensitivity in brightly lit environments or disabling glare during the day to glare with oncoming headlights at night
Myopic shift- increase the diopteric power of the lens resulting in a mild-to-moderate degree of myopia- this so-called second sight in presbyopic patients is associated with nuclear sclerotic cataract
Monocular diplopia- when nuclear changes are concentrated in the inner refractile area in the centre of the lens

10
Q

What are the investigations used for cataracts?

A

History and slit lamp examination
Lab tests to detect comorbidities
Occular B-scan US- a posterior pole pathology is suspected and an adequate view of the back of the eye is obscured by the dense cataract- this is helpful in palnning out the surgical management and providing a more guarded post-operative prognosis for the visual recovery of the patient
An accurate biometry (axial length and keratometry) should be performed to calculate for the IOL power to be used- the power of the IOL on the operated eye must be compatible with the refractive error of the fellow eye to avoid complications- eg. post-operative anisometropia
Corneal integrity, specifically the endothelial layer- slit lamp examination. pachymetry and specular microscopy to predict post-operative corneal morbidities to weigh the risks vs. benefits of performing cataract extraction- eg. corneal oedema or corneal decompensation

11
Q

Which medical agents are being investigated for the treatment of cataracts?

A
aldose reductase inhibitors
sorbitol-lowering agents
aspirin
glutathione-raising agents 
anti- oxidant vitamins C & E
12
Q

What is intracapsular cataract extraction (ICCE) ?

A

ICCE is now reserved in cases where zonular integrity is impaired severely to allow successful lens removal and IOL implantation in ECCE
larger limbal incisions and subsequent risk of delay in healing, visual rehabilitation, significant astigmatism, post-operative would leaks, post-operative cystoid macular oedema (CME), retinal detachment and post-operative corneal oedema made it unpopular

13
Q

What is extracapsular cataract extraction (ECCE)?

A

Involves the removal of the lens nucleus through an opening in the anterior capsule with retention of the integrity of the posterior capsule
a smaller incision leads to less trauma to the corneal endothelium, better anatomic placement of IOL (within an intact posterior capsule), reduces the incidence of CME, retinal detachment, endophthalmitis

14
Q

What is phacoemulsification (PE)?

A

Both ECCE and PE are similar in that extraction of the lens nucleus is performed through an opening in the anterior capsule or by anterior capsulotomy followed by irrigation and aspiration of cortical material and placement of the IOL in the posterior capsular bag
PE uses smaller incisions, affording more rapid would healing and faster visual rehabilitation  a relatively closed system allows a better control of IOP, safeguards against +ve vitreous pressure and choroidal haemorrhage

15
Q

What isphacoemulsification (PE)?

A

Both ECCE and PE are similar in that extraction of the lens nucleus is performed through an opening in the anterior capsule or by anterior capsulotomy followed by irrigation and aspiration of cortical material and placement of the IOL in the posterior capsular bag
PE uses smaller incisions, affording more rapid would healing and faster visual rehabilitation- a relatively closed system allows a better control of IOP, safeguards against +ve vitreous pressure and choroidal haemorrhage

16
Q

What are the complications of phacoemulsification (PE)?

A
Posterior capsule opacification (20%)
Vitreous loss (4%)
Retinal detachment (1%)
Endophthalmitis (0.1%)
17
Q

What is acute bacterial endophthalmitis?

A

Pain and marked visual loss with an absent or poor red reflex
corneal haze, hypopyon and exudates
Staph epidermidis, Staph aureus and Pseudomonas sp
treated with intravitreal antibiotics
Inv: Occular B scan

18
Q

What are the stages of development for cataracts?

A

Immature- lens in partially opaque
Mature- lens is totally opaque
Hypermature- lens material has become shrunken and the lens capsule is wrinkled due to leakage of water out of the lens
Morgagnian cataract- hypermature cataract in which total liquefaction of the cortex has allowed the nucleus to sink inferiorly

19
Q

What is posterior capsule opacification?

A

Occurs between 10-50% of cases (average 20%) within 3 years of surgery
When patient becomes sympotmatic treatment is with YAG laser

20
Q

What are the common types of metabolic cataracts?

A

Diabetes: age related (appears earlier) or true diabetic cataract (snowflake opacities)
Galactosaemia: due to GPUT deficiency- presents with oil droplet cataract
Galactokinase deficiency: associated with lamellar opacities
If metabolic defect is detected and treated within 3 months then the lens changes are reversible
(Manosidosis, Fabry’s disease, Lowe’s, Wilson’s or hypocalcaemic syndromes)

21
Q

How do drugs affect cataracts?

A

Corticosteroids: PSC
Chlorpromazine: fine yellow deposits anterior lens capsule
Chemotherapy: eg. Buslphan

22
Q

How are the signs in cataracts affected by other diseases?

A

Uveitis: anterior, cytomegalovirus, toxoplasmosis, rubella
Hereditary retinal degenerations: retinitis pigmentosa, Gyrate atrophy, Stickler’s syndrome
High myopia: Glaucomflecken – small grey whit anterior subcapsular cataract
Post-surgical: glaucoma, parsplana vitrectomy

23
Q

What systemic diseases are cataracts associated with?

A

Cutaneous disease: congenital ectodermal dysplasia, Werner’s & Rothmund-Thomson’s syndrome
and atopic dermatitis (no eye lashes and swollen eyelids)
Connective tissue/skeletal disorders: myotonic dystrophy (Christmas tree pattern), Conradi’s,
Stickler’s and Marfan’s syndromes
Central nervous system: Marinesco-Sjorgren’s syndrome and neurofibromatosis type 2
Down’s syndrome